When building data networks to support voice-over-IP (VoIP) communications it is often desirable to place the IP Phones in a separate VLAN from the other data devices in the network. This makes it easier for the switches in the network to provide the Quality of Service processing needed to ensure proper transmission of VoIP calls. The switches in the network are configured with the VLAN dedicated for VoIP traffic. The VLAN to which an IP phone belongs is identified using an IEEE 802.1Q tag with the VLAN value in the Ethernet frames, for example, generated by the device. After being assigned, the VLAN value is placed in the header of substantially all frames transmitted by the IP phone.
Unfortunately, the current protocols defined for distributing VLAN information between switches do not provide a mechanism to inform end users which VLAN should be used for purposes of sending traffic. The VLAN identification must therefore be manually configured in each VoIP phone either directly or through a network management tool. Such practices are both time consuming and raise the potential for human error. To add to the burden, it may be necessary to reconfigure an IP phone with a new VLAN if the IP phone is moved to a different switch or if the VoIP VLAN configuration of the switch is changed.
There are mechanisms for distributing information between switches about the VLANs configured on the respective switches and for distributing the information between switches to construct a topologic map of the network, for example. The Group Address Resolution Protocol (GARP) VLAN Address Resolution Protocol (GVRP) standardized by the IEEE in IEEE Standard 802.1Q-1998-IEEE Standards for Local and Metropolitan Area Networks: Virtual Bridged Local Area Networks provides a mechanism for conveying information between switches in the network about the IEEE 802.1Q VLANs configured on the switches and on which ports of the respective switches these VLANs are configured. In particular, the IEEE 802.1Q standard defines an architecture for Virtual Bridged LANs, the services provided in Virtual Bridged LANs, and the protocols and algorithms involved in the provision of those services. However, no such mechanism has been defined for communicating VLAN configuration information from a network device to an end system.
In addition to communicating VLAN configuration information to a VoIP phone, it is also desirable to communicate physical location information from the phone to an IP private branch exchange (PBX). Enhanced 911 solutions, for example, require that phone systems such as IP PBXs provide physical location information with a 911 call using a mechanism called the automatic location indicator (ALI). The ALI allows an emergency service provider to automatically determine the physical location of the person placing the 911 call. The current state of the art for associating physical location information with the phone number that identifies a telephone uses an external database. The PBX then consults this external database when processing a 911 call to extract the physical location information associated with the telephone placing the 911 call. The location information in the external database must be manually entered and is inaccurate when a phone is moved to new locations in the network until the database is manually updated.
There is therefore a need for a system and method to automatically communicate VLAN information to IP phones and to automatically convey physical connectivity information to a central store with minimal human intervention, minimal delay, and maximal accuracy.